• Re-enable Proxy ARP.
INTERFACE mode
ip proxy-arp
To view if Proxy ARP is enabled on the interface, use the show config command in INTERFACE mode. If
it is not listed in the show config command output, it is enabled. Only non-default information is
displayed in the show config command output.

Clearing ARP Cache

To clear the ARP cache of dynamically learnt ARP information, use the following command.
• Clear the ARP caches for all interfaces or for a specific interface by entering the following information.
EXEC privilege
clear arp-cache [interface | ip ip-address] [no-refresh]
–ip ip-address (OPTIONAL): enter the keyword ip then the IP address of the ARP entry you
wish to clear.
–no-refresh (OPTIONAL): enter the keywords no-refresh to delete the ARP entry from CAM. Or
to specify which dynamic ARP entries you want to delete, use this option with interface or ip
ip-address.
– For a port channel interface, enter the keywords port-channel then a number from 1 to 128.
– For a 10-Gigabit Ethernet interface, enter the keyword TenGigabitEthernet then the slot/port
information.
– For a VLAN interface, enter the keyword vlan then a number between 1 and 4094.
– For a 40-Gigabit Ethernet interface, enter the keyword fortyGigE then the slot/port information.
NOTE: Transit traffic may not be forwarded during the period when deleted ARP entries are resolved
again and re-installed in CAM. Use this option with extreme caution.
ARP Learning via Gratuitous ARP
Gratuitous ARP can mean an ARP request or reply.
In the context of ARP learning via gratuitous ARP on the system, the gratuitous ARP is a request. A
gratuitous ARP request is an ARP request that is not needed according to the ARP specification, but one
that hosts may send to. Gratuitous ARP can:
• detect IP address conflicts
• inform switches of their presence on a port so that packets can be forwarded
• update the ARP table of other nodes on the network in case of an address change
In the request, the host uses its own IP address in the Sender Protocol Address and Target Protocol
Address fields. When a gratuitous ARP is received, the system installs an ARP entry on the CPU.
To enable ARP learning via gratuitous ARP, use the arp learn-enable command in CONFIGURATION
mode.
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